Vehicle arresting device

ABSTRACT

A vehicle arresting device comprises a net intended to be laid flat on the ground in the path of an oncoming vehicle to be arrested. Two rows of barbed spikes are attached to the net along its leading edge. When a vehicle runs over the device the spikes lodge in its front tyres and the net is caused to wrap around the front wheels, eventually being pulled tight under the vehicle so that the tension in the net prevents further rotation of the wheels and the vehicle is brought to a stop. The net is manufactured such that in its deployed condition it has sufficient lateral stretch to allow it to become fully wrapped around the front wheels before the tension builds up to a level at which there might otherwise be a risk of the spikes being pulled from the tyres.

The present invention relates to vehicle arresting devices, such as maybe deployed by law enforcement agencies to safely stop the progress of asuspect vehicle for example if stolen or engaged in other criminalactivity.

Vehicle pursuit is one of the most common high-risk areas of lawenforcement and many people are killed each year as a result of highspeed chases. An alternative method for stopping, or attempting to stop,a fleeing vehicle which is quite widely practised is to deploy on theroadway ahead of the vehicle a device intended to puncture its tyres. Acommon form of this type of device comprises a lightweight plasticslatticework which is laid across the road and carries a number oftubular spikes. When the target vehicle passes over the device some ofthe spikes penetrate its tyres and are carried along with the vehicleenabling deflation of the respective tyre(s) through their hollowconstruction. While tyre deflation significantly retards a vehicle andmakes it difficult to control, devices of this kind do not necessarilyresult in the vehicle being stopped, or may do so only after the suspecthas been able to continue driving “on the rims” for a considerabledistance further.

Another form of device intended for more positive arresting of theprogress of a vehicle is proposed in U.S. Pat. No. 6,220,781. Thisdevice comprises a panel of lightweight material, such as silk, to belaid on the roadway and having a tactile surface at its leading edgeformed from barbed pins and/or adhesive blisters. A split seam extendsthrough the panel from the centre of its leading edge to approximatelythree-quarters of its length (in the fore and aft direction) and areinforcement sash of Kevlar® or similar material is affixed to thepanel and extends in a partial loop around the split. The intention isthat when a vehicle encounters this device its leading edge will adhereto the front wheels so that the panel will wrap around the wheels until,when the limit of the split seam is reached, the reinforcement sash isdrawn tight under the vehicle thereby preventing further rotation of thewheels. It is essential to this operation, however, that the vehicleencounters the device with its front wheels disposed either side of thesplit seam, and important that they run directly over the relativelynarrow reinforcement sash in order to ensure that the latter becomeswrapped around the wheels. In other words the operation is sensitive tothe correct lateral positioning of the vehicle relative to the device,and it is likely to be successful only where the vehicle can beconstrained to pass through a relatively narrow gap where the device isdeployed.

The present invention seeks to overcome the above-mentioned drawbacks ofthe prior art and in a first aspect resides in a vehicle arrestingdevice comprising a net adapted to be laid flat on the ground in thepath of a vehicle to be arrested with one or more transverse rows ofupwardly-directed spikes attached to the net at a leading portionthereof, the loops of said net being oriented with a longer dimension inthe fore and aft direction than in the transverse direction, whereby inuse any widthwise portion of the net is capable of substantialtransverse elongation.

In a second aspect the invention resides in a method of arresting avehicle which comprises laying a device according to the first aspect ofthe invention on the ground in the path of the vehicle such that whenthe front tyres of the vehicle run over the leading portion of thedevice one or more said spikes become embedded in each said tyre, thenet becomes wrapped around the front wheels of the vehicle, and theportion thereof between the wheels of the vehicle is pulled tight underthe vehicle, thereby preventing further rotation of those wheels.

By virtue of the transverse stretchability of the net in a deviceaccording to the invention it can readily absorb the loads which areimposed on it as it pulls tight under a vehicle in use of the device,and readily ensure that it is fully wrapped around the vehicle's wheelsbefore pulling tight. Furthermore the device can be effective to arresta vehicle irrespective of the particular position across its width overwhich the front tyres of the vehicle run and is not limited in thisrespect to the critical relative positioning of a split seam andreinforcement sash as in the case of the device of U.S. Pat. No.6,220,781.

In another aspect the invention resides in a method of constructing avehicle arresting device according to the first aspect of the inventionwhich comprises: taking a net and deforming the same to elongate theloops thereof in the intended fore and aft direction of the device whilereducing the dimension of the net in the intended transverse direction;and attaching elongate elements of flexible material between oppositeside edges of the net, whereby to retain the net in such deformedcondition when laid on the ground in preparation for arresting avehicle.

In a further aspect the invention resides in a spike assembly for use ina vehicle arresting device comprising a base portion whereby the spikecan be stood in an upwardly-directed orientation, a shaft portionextending from said base portion and a generally pyramidal barb portionat the tip of said shaft portion.

These and other features of a vehicle arresting device according to theinvention will now be more particularly described, by way of example,with reference to the accompanying drawings of a preferred embodimentthereof and in which:

FIG. 1 is a plan view of a preferred form of vehicle arresting device inits deployed configuration;

FIGS. 2 and 3 are respectively a side elevation and an underneath planview of a typical spike assembly incorporated in the device of FIG. 1,to an enlarged scale;

FIGS. 4 and 5 are respectively a side elevation and a top plan view ofthe spike in the assembly of FIGS. 2 and 3, to a further enlarged scale,and FIG. 6 is a partial section on the line VI-VI of FIG. 5;

FIG. 7 is a view to an enlarged scale of the region of the deviceindicated at ‘X’ in FIG. 1;

FIG. 8 is a section on the line VIII-VIII of FIG. 7, to a furtherenlarged scale;

FIG. 9 is a view to an enlarged scale of the region of the deviceindicated at ‘Y’ in FIG. 1, from beneath; and

FIGS. 10(a) and 10(b) illustrate schematically the configuration of thenet incorporated in the device of FIG. 1 in its natural woven conditionand in the condition in which it is assembled respectively.

With reference to FIG. 1 there is shown a plan view of a vehiclearresting device in accordance with the invention in its deployedconfiguration, that is to say laid flat upon the ground with theintention of arresting a vehicle travelling in the direction of arrow A.The device comprises a net 1 of rectangular planform (the mesh of whichis illustrated only schematically in FIG. 1 but is more accuratelydepicted in FIGS. 7 and 9). The net 1 is preferably woven from highbreaking strain braided polyethylene and is similar in this respect tocommercial fishing netting. In the illustrated condition the overallshape of the net is maintained by strips of flexible material 2, 3, 4,5, 6 and 7 attached respectively at its leading and trailing edges (inthe sense of its orientation to oncoming traffic), side edges andtransversely at two intermediate locations. At the leading edge thereare two transverse rows of upwardly-directed hardened steel spikes 8,the form of which will be more particularly described with reference toFIGS. 2 to 6. Tapes 9 are also attached to the strips 2, 3 and 4 at theleading, trailing and one side edge in order to facilitate the manualfolding and deployment of the assembled device.

With reference to FIGS. 2 and 3 each spike 8 is part of an assembly 10comprising also a perforated steel base 11 welded to the respectivespike. The relatively wide base 11 helps to ensure that the spikeremains upright when the device is laid on the ground, and is perforatedto minimise the weight of the assembly. As shown in FIGS. 4 to 6, eachspike 8 is machined to define a shaft 12 tipped with a sharply pointed,generally pyramidal barb 13. More particularly the barb 13 is polygonalin planform, being machined from a solid cone to provide three majorflat faces 13A between three minor frustoconical faces 13B with a commonvertex 13C, and is undercut at its base as indicated at 13D in FIG. 6.This form of barb with flats 13A machined into a cone has been found torequire less force to penetrate conventional tyre rubber than theequivalent plain cone.

FIGS. 7 and 8 show the relationship of the net 1, spike assemblies 10and leading edge strip 2. In each row there is a spike 8 located at eachalternate knot across the width of the net 1, with the two rowslaterally offset from each other by one knot. The spikes are held on thestrip 2 at the correct spacing by multiple hook and loop contactfastener material such as that known under the registered trade markVelcro. Lengths of Velcro® hook material 14 (FIG. 8) are sewn to theleading edge strip 2 where the two rows of spikes are required and thespike assemblies 10 are attached by respective pads of Velcro® loopmaterial 15 passing over the spike assembly bases 11 and into contactwith the hook material 14, the pads 15 being apertured to pass thespikes 8. Holes 16 and 17 are shown cut through the material of thestrip 2 and (in the case of holes 17) through the associated Velcro®fasteners in FIGS. 1 and 7 to reduce both the weight of the overallassembly and any aerodynamic forces due to wind acting on the leadingedge of the device when deployed.

Having attached the spike assemblies 10 to the leading edge strip 2 theyare assembled with the net 1 by thrusting the barb 13 of each spikethrough the respective knot of the net and passing the knot down toengage frictionally around its shaft 12, as shown for the knot 1A inFIG. 8. A plastics tube 18 is passed over the exposed length of eachspike 8 to resist lifting of the net along the shaft 12 and to preventthe barb 13 snagging on the net when it is folded for storage andtransportation.

FIG. 9 shows the relationship of the intermediate strip 6, net 1 andside strip 4, the equivalent applying to the opposite side strip 5 andfor the trailing edge strip 3 and other intermediate strip 7. The strip6 comprises a length of webbing which is threaded through loops of thenet 1 across its width as illustrated. At each side edge the respectivestrip 4 or 5 is folded over the net 1 and over the ends of the strips 2(see also FIG. 7), 3, 6 and 7, and glued thereto. To further anchor theside strips 4 and 5 to the ends of the strips 3, 6 and 7 rivets 19 areapplied, passing through the material of the respective strips and alocal loop of the net. At the leading edge, the side strips 4 and 5 areapertured to pass the outermost spikes 8A, 8B in each row, as shown forthe strip 5 in FIG. 7.

The illustrated device is designed to be man-portable and is normallykept folded in an appropriate backpack, from which it can rapidly beunfolded and deployed across a roadway when a target vehicle is to bearrested.

In use, when a vehicle encounters the deployed device from the directionof arrow A in FIG. 1, its front tyres will run over a number of adjacentspikes 8 in each of the rows. As a respective spike is encountered thesurrounding tube 18 (FIG. 8) is crushed down by the tyre, allowing thespike to penetrate the tyre. The barb 13 is shaped to facilitate entryof the spike into the tyre, and its undercut 13D (FIG. 6) is designed tocatch on the conventional steel braiding within a tyre carcass to resistremoval. The net 1 therefore becomes attached to the wheels of thevehicle at two locations across its width, being trapped between thebases of the respective spike assemblies and the tyres in which thespikes are embedded. Continued movement of the vehicle therefore causesthe net to wrap around the front wheels and the portion between thewheels is pulled tight under the vehicle until its tension preventsfurther rotation of the wheels, thereby bringing the vehicle to a stop.In practice this occurs in a similar distance to an emergency stop as ifthe vehicle's brakes had been applied.

It is important to the successful operation of the device that the net 1has sufficient lateral stretch to absorb the loads that are imposed onit as it pulls tight to arrest a vehicle, and to allow the net to becomefully wrapped around the front wheels before the tension builds up to alevel at which there might otherwise be a risk of the spikes 8 beingpulled from the tyres. In this respect it will be noted from FIGS. 7 and9 that in the initial deployed condition of the device the loops of thenet are in a diamond shape with the longer dimension in the fore and aftdirection. It is therefore capable of significant lateral elongationbefore the loops are pulled to a condition in which their longerdimension is in the transverse direction and the net begins to tighten.More particularly, the “natural” form of the loops in which the net isoriginally woven is rectangular with the longer dimension in thetransverse direction, as schematically depicted in FIG. 10(a) (where thesize of the loops is greatly exaggerated in relation to the overall sizeof the net for ease of illustration). In the course of assembly of thedevice, before the strips 2 to 7 are attached, the net is pulled out ofthe “natural” shape of FIG. 10(a) and held in a jig in the less elongateaspect ratio schematically depicted in FIG. 10(b) in which it issubsequently retained by the attachment of the strips 2 to 7. Note,however, that the presence of these strips does not prevent the portionof the net between the wheels of a vehicle elongating laterally in useof the device because it is not constrained in that sense by positiveattachment to the strips 6, 7 and 3 intermediate its attachment to theside strips 4 and 5, and at the leading edge its attachment to strip 2is by means of the Velcro® pads 15 over the bases of the spikes 8 whichcan pull off from the Velcro® material 14 as the net stretches.

It will also be noted that the device can operate to arrest a vehicle asdescribed above so long as both front tyres run over its leading edge,irrespective of the position across the width of the device where thisactually occurs.

In order to enhance the initial attachment of the net 1 to the vehicle'styres its leading edge may be formed with a series of short longitudinalcuts spaced across its width, as schematically indicated at 1B inFIG. 1. By this means only the respective section of the net between theadjacent cuts has to be lifted by the tyre during the initial part ofits rotation after contacting the spikes 8, which further minimises therisk of the spikes being pulled from the tyre.

1. A vehicle arresting device comprising a net adapted to be laid flaton the ground in the path of a vehicle to be arrested with one or moretransverse rows of upwardly-directed spikes attached to the net at aleading portion thereof, the loops of said net being oriented with alonger dimension in the fore and aft direction than in the transversedirection, whereby in use any widthwise portion of the net is capable ofsubstantial transverse elongation.
 2. A device according to claim 1wherein said spikes are tipped with generally pyramidal barbs.
 3. Adevice according to claim 2 wherein said barbs comprise a plurality offlat triangular side faces separated by frustoconical side faces.
 4. Adevice according to claim 2 wherein said barbs are undercut at theirbases.
 5. A device according to claim 1 wherein said spikes arecomprised in spike assemblies comprising a base portion whereby therespective spike can be stood in an upwardly-directed orientation, ashaft portion extending from the base portion and a barb portion at thetip of the shaft portion.
 6. A device according to claim 1 comprising aplurality of elongate elements of flexible material extendingtransversely of the net at spaced locations and attached to the net atits opposite side edges.
 7. A device according to claim 6 wherein one ormore of said elongate elements is threaded through loops of the netbetween said side edges but more positively attached to the net at saidside edges.
 8. A device according to claim 6 wherein one or more of saidelongate elements is held to the net between said side edges by virtueof separable hook and loop material but more positively attached to thenet at said side edges.
 9. A device according to claim 6 wherein saidspikes are comprised in spike assemblies comprising a base portion andan upwardly-directed shaft portion and said spike assemblies areattached to a said elongate element at a leading portion of the net bymeans of separable hook and loop material, elements of which materialare interengaged with said base portions of respective spike assemblieslocated therebetween.
 10. A device according to claim 5 wherein saidspike assemblies are attached to the net by penetrating respectiveportions of the net such that the material of the net encircles theshaft portions of those assemblies.
 11. A device according to claim 1wherein said spikes are surrounded by respective tubes which are adaptedto be crushed to permit penetration of the respective spikes into avehicle tyre running over such spikes in use of the device.
 12. A deviceaccording to claim 1 wherein said net is formed into a plurality ofseparate widthwise sections at said leading portion thereof.
 13. Amethod of constructing a vehicle arresting device comprising a netadapted to be laid on the ground in the path of a vehicle to be arrestedwith one or more rows of upwardly-directed spikes attached to the net ata leading portion thereof, the method comprising: taking a net anddeforming the same to elongate the loops thereof in the intended foreand aft direction of the device while reducing the dimension of the netin the intended transverse direction; and attaching retainers to retainthe net in such deformed condition when laid on the ground inpreparation for arresting a vehicle.
 14. A method according to claim 22which comprises threading one or more said elongate elements throughloops of the net between said side edges but more positively attachingsuch element(s) to the net at said side edges.
 15. A method according toclaim 22 which comprises holding one or more said elongate elements tothe net between said side edges by virtue of separable hook and loopmaterial but more positively attaching such element(s) to the net atsaid side edges.
 16. A vehicle arresting device constructed by a methodaccording to claims
 13. 17. A method of arresting a vehicle whichcomprises laying a device according to claim 1 on the ground in the pathof the vehicle such that when the front tyres of the vehicle run overthe leading portion of the device one or more said spikes becomeembedded in each said tyre, the net becomes wrapped around the frontwheels of the vehicle, and the portion thereof between the wheels of thevehicle is pulled tight under the vehicle, thereby preventing furtherrotation of those wheels.
 18. A spike assembly for use in a vehiclearresting device comprising a base portion whereby the spike can bestood in an upwardly-directed orientation, a shaft portion extendingfrom said base portion and a generally pyramidal barb portion at the tipof said shaft portion.
 19. A spike assembly according to claim 18wherein said barb portion comprises a plurality of flat triangular sidefaces separated by frustoconical side faces.
 20. A spike assemblyaccording to claim 19 wherein said barb portion is formed by machiningsaid flat faces from a conical form.
 21. A spike assembly according toclaim 18 wherein said barb portion is undercut at its base.
 22. A methodaccording to claim 13 wherein said retainers are elongate elements offlexible material attached between opposite side edges of the net.